Controls for machine tools



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Aug. 17, 1965 Filed Feb. 15, 1961 CONTROLS J. C. HOLLIS FOR MACHINE TOOLS TPAVEPSE //f/Y (Wifi/P716? .5W/7654455 L Il 1574/? lr/ 00/-7999 15 Sheets-Sheet 13 United States Patent O 3,206,921 CONTRGLS FR MACHINE TOLS John C. Hollis, Milwaukee, Wis., assigner to Giddings & Lewis Machine Tool Company, Fond du Las, Wis., a corporation of Wisconsin Filed Feb. 15, 1961, Ser. No. 89,449 13 Claims. (Cl. 192-142) This invention relates to improvements in systems for causing machine tools to execute automatically repetitive cycles :of machining operations made up of a plurality of successive machining steps.

Control systems have been known heretofore for operating a machine tool automatically to repeat a series of steps initially carried out under the control of a machinist. Such control systems conventionally include means for recording the performance of the machine tool on a suitable medium so that the record may be played back in order to control the tool in the repeat cycle. While the present control system may be classified in general with this known type of system, it is now proposed that the operator will set into control system recording means, the data required to direct the tool to repeat each machining step.

One object of this invention is to provide control means with which a machine tool may be operated in a manner closely simulating the usual manner of operation by hand, so that to set up the program for the repeat cycle, the operator carries out, by hand, a series of steps to machine a workpiece. Another object is to provide a simplifed means for an operator to record the data as to each machining step at the time the step is carried out manually without the necessity for extensive calculations to provide data in acceptable form for the machine tool control recording means.

Program preplanning, therefore, may be dispensed with entirely and the machining operation including determining operation sequence, selecting tool elements, and selecting suitable feeds and speeds carried out under the manual direction of the machinist. Widely diverse machine tool operations may be carried out with less complex information storage and tool control system components because the repeat cycle simply mimics the manually directed machining steps.

Another important object is to provide an analog to digital converter for end point control of a machine tool element with an improved means for reducing the velocity of such element before the element reaches an end point or stopping position, thereby avoiding overshoot.

Other objects and advantages will become apparent as this description proceeds, taken with the drawings, in which:

FIGURE l is an elevational view illustrating a vertical turret lathe with a control system according to this invention;

FlG. 2 diagrammatically illustrates the tool drive;

FlG. 3 illustrates a fragment of the tool control panel;

FIG. 4 and 5 illustrate the control panel mechanism;

FIG. 6 diagrammatically shows an analog digital converter transmission;

FIG. 7 is a longitudinal sectional view of the analog to digital converter;

FIG. 8 is a fragmentary longitudinal sectional view of the converter with certain parts removed;

FIG. 9 is a transverse sectional view taken substantially in the plane of lines 9-9 of FIG. 7 through the fingers to show the auxiliary slowdown switches;

FIG. 10 is a transverse sectional view taken substantially inthe plane of lines Iii-l0 of FlG. 7 through the ring gear of the fine section;

FiG. l1 is a transverse sectional view taken substan- 3,209,921 Patented Aug. l?, i965 tially in the plane of lines 1lill of FIG. 7 adjacent the first cam and the line section;

FiG. 12 is a fragmentary transverse sectional view taken substantially in the plane of lines 12-12 of FIG. 7 adjacent the fourth cam in the medium fine section;

FIG. 13 is a fragmentary elevational View of parts in section taken substantially in the plane of lines 13--13 of FIG. l1 looking down on the third switch of the tine section;

FIG. 14 is a perspective view of the stack of converter cams of the converter coarse section;

FiGS. 15-18 diagrammatically illustrates the four sets of cams comprising a converter cam stack;

FG. 19 is a chart depicting in binary notational form the successive states of the converter switches;

FG. 20 is a fragmentary sectional view taken substantially in the same plane as FIG. 11 and showing all fingers reflected outwardly by the converter rods;

FIGS. 2l, 22 and 23, when joined together in edge-toedge relation, comprise a schematic wiring diagram of the control system;

FiGS. 24-28 diagrammatically illustrate successive steps of a machining process;

FIG. 29 is a chart giving data for the machining steps of FIGS. 24-28; and

FIG. 30 is a chart illustrating converter slowdown switches actuation.

While the invention has been shown and will be described in some detail with reference to a particular embodiment thereof, there is no intention that it thus be limited to such detail. On the contrary, it is intended here to cover all alternatives, modifications and equivalents falling within the spirit and scope of the invention as deiined by the appended claims.

GENERAL ORGANIZAHON In order that the invention and its advantages may be fully understood, the background setting or environment for one specific application of the invention will first be briefly considered, particularly with reference to an exemplary machine tool. It will be understood, however, that the invention may be applied in a straightforward manner in other speciiic environmental settings and with types of machine tools other than .the one here shown.

The machine tool here shown by way of example is a vertical turret lathe 2) (FIGURE l) which, in general terms, includes a rotatable member or table 21 journaled for rotation about a vertical axis in a base 22 and adapted by means such as chuck jaws 23 to rigidly support a Workpiece (not shown). Rising above the table 21 are columns 24 connected at their upper ends by a crosspiece 25 and supporting a vertically adjustable c-rossrail 2o. The rail is formed with way surfaces 28 which slidably Support a translatable element or saddle 3l) for movement in a horizontal direction. The saddle, in turn, slidably supports a vertically movable ram 3l which carried an angularly positionable turret 32 adapted to carry a plurality of cutter tools selectively positionable in the downwardly extending working position. As here shown, a tool holder 34, carried by the turret 32, is adapted to receive a cutter which can machine the workpiece on the rotating table 2l to different diameters and accomplish facing cuts along surfaces disposed radially of the table axis.

The ram 3l is vertically positionable within the saddle by rotation of a lead Screw 35, while the saddle 3i) is horizontally positionable in response to rotation of an associated lead screw 36. The lead screw 36 is adapted to be driven in either direction and at any of a plurality of angular velocities in order to impart different feed rates o r linear velocities to the saddle 3i?. For this purpose, a multi-speed feed transmission is disposed with a housing Appropriate position indicators are disposed on the machine tool. A scale 46B which rotates in proportion to vertical movement of the corresponding tool holder and thus indicates its position, and a second scale and dial 4l which rotates in proportion to the horizontal movement of the corresponding tool holder and thus indicates its horizontal position.

For further details regarding the organization and operation of the turret lathe Ztl, lreference may be had to Hollis Patent No. 2,831,361, issued April 22, 1958; and to the copending continuation-in-part application of John C. Hollis, Serial No. 54,811, now Patent No. 3,027,782, tiled August 31, 1960, and assigned to the assignee of the present application. For further details of a suitable power turret, reference may be made to Conover Patent No. 2,936,656. While the features of the present invention may be applied to the control of motions and positions of several other movable elements such as the side head 42, they will, for brevity, be described here only in relation to the feeding and positioning of the saddle 30 .and the ram 31 in coordination with rotation of the table 2l. Moreover, this description will be confined to the vdetails of the means for positioning the ram or saddle .under power, for further details of the mechanism for power setting, reference may be made to the abovementioned Hollis patent.

Table speed transmission The rotatable member or table 21 (FIGURE l) is adapted to'be driven at any one of a plurality of rotation speeds. In order to understand how this is accomplished byy electrical controls, a multi-speed tab-le transmission having a plurality of electromagnetically operated clutches is illustrated in FIG. 2. As there shown, a prime mover or electric motor 43 has its output shaft 44 drivingly connected to a shaft 45 with either of two drive ratios in response to selective energization of speed clutch coils SC-l or SC-la. With neither coil energized, the transmission is in neutral as shown in FIG. 2. Energization of either coil SC-l or SC-la shifts an armature 46 or V 46a and causes driving engagement of a clutch member 47 splined to the shaft 45 with either of two gears 4S or'49 journaled on that shaft. spectively meshed with gears Sti and 51 fast on the motor shaft 44 so that the shaft 4S Vwill be driven fromV the motor shaft 44 at either `of two speeds depending upon.

whether the clutch coils SC-il. or SC-la are energized. With both coils deenergized, springs 52, 52a hold the clutch member 47 in a neutral position free from engagement with either gear d8, 49;

In a similar manner, a clutch assembly controlled by a clutch coil YSC-Z is interposed between the shaft t5 and a third shaft 53, so that vthe latter may be driven at any of four speeds depending upon the particular combination of the clutch coils SC-l, SC-la, SCA-2 which are energized. Thus the shaft d5 is drivingly connected to the third shaft S3 at either of two drive ratios in response to energization or deenergization of the speed clutch coil SC-Z. Energization of that coil shifts an armature 54 against the bias of a spring 55 and causes driving engagement of a clutch member 56 splined to the shaft 53 with a gear SS journaled on that shaft. When the clutch coil SC-2 is deenergized, the spring S5 holds the fclutch member 56 in driving engagement with a second gear 57 journaled on the shaft 53. The gears 57, 5S are drivingly engaged by gears dil, 61 fixed on the shaft 45. Further, the shaft 53 carries gears d2, 63 which are in driving relation with a shaft 64 through a similar clutch assembly '65 controlled by a clutch coil SiC-3. Finally,

thel shaft 64 is drivingly connected to an output shaft 67 Y through a clutch assembly 6,3 controlled by an associated clutch coil SC-d so that for each speed ofthe shaft 64 the output shaft 67 may be driven at either of two speeds,

The gears 48 and 49 are re- 4 Y meshing with a beveled ring gear 7l) rigid with the table 2l.

A normally disengaged brakeV 7l is associated with the table to stop the table by engaging the brake with the table drive in neutral. The brake 71 is operated by energizing the brake coil BR.

lt will be apparent that depending upon the particular one of sixteen (plus a neutral) possible combinations of the five clutch coi-ls SC-l, SC-lla, SC-2, SC-Zl, SC-i which are energized, the table may be driven at any one of sixteen possible rotational Vspeeds ranging, illustratively, from 24 to 320 revolutions per minute.

The multi-speed trnasmission of FIG. 2 is only diagrammatically illustrated, and a more detailed preferred organization is shown and described in the above-identified Hollis application.

Saddle feed and ram feed transmission The multi-speed feed transmission for translating the saddle 30 in or out in the Z direction, and the ram 31 up or down in the Y direction and at any of a plurality of relative feed rates may be of the type disclosed in the above-identified Hollis patent. To facilitate an understanding of the present invention, such feed transmission is diagrammatically illustratedin FIG. 2,'having an input member in the form of a gear 72 which is meshed with and driven by the beveled ring gear 7i) fixed to the table 21. Therefore, .the input to the saddle and ram feed transmission is always at a speed which is related to the table speed. Drivingly connected between the input shaft 74 and a drive shaft 76, which is adapted to be coupled todrive either the saddle lead screw 36 or the ram lead screw 35 or to drive both the saddle lead screw 36 and the ram lead screw 35 simultaneously, are four two-speed gearing and clutching assemblies 82, 83, 84, 85, respectively, controlled by five feed clutch coils FCl-S, FCI-F, FCZ, FC3, FC4. The gearing and clutching assemblies are here shown as identical to such assemblies of the table transmission'also shown in FIG. '2, and therefore need not be described in detail. It isV sufficient to note 'only that, for a given speed of the input shaft 74 (i.e., a given speed of the table 21), the final shaft 76 may be driven at any of sixteen possible speeds or rates depending upon the particular combination of the five clutch coils FCI-R'FCl-S and FC2-FC4 which are energized.

In order to control starting and stopping of the saddle 30, and the direc-tion of its movement, the shaft '7'6 is drivingly connected through two normally disengaged forward and reverse clutches 86, 88 to the saddle lead screw 3d which is threadably engaged withfa nut 30a connected to the saddle. Energization of theV forward clutch coil Z-I- shifts a clutch member 88 splined to the lead screw '36 intoengagement with the teeth 88a of a gear @Sb journaled on that screw and coupled through an idler gear 89 to a gear 76k fixed to the shaft 76. This will drive the saddle lead screw 36 in a forward direction, i.e.,

depending upon whether the clutch coil SC-4 is energized Y or deenergized. The output shaft 67 carries a Vpinion 69 in from right to left in FIG. 2. Alternatively, energization of a clutch coil Z- will shift a clutching member 86 splined to the lead screw 36 into engagement with the teeth 86a of a gear Sb journaled on that screw and meshed with a gear-76a rigid with the shaft 76. This will cause the lead screw 36 to rotate in such a direction as to move the saddle 30 out, i.e., from left to right. When neither of the clutch coils Z+ `or Z- is energized, then the saddle 3l) will be stopped, even though the table is rotating.

Likewise, in order to control starting and stopping of the ram 31, and the direction of its'movement, the shaft 76 is drivingly connected through two normally disengaged forward` and reverse clutches 93, 92 tothe lead screw 35 which is threadably V'engaged with a nut 31a connected to the ram. The forward and reverse clutches for the ram lead screw 35 operate inv a manner similar to the operation of the forward and reverse clutches for the saddle lead screw '36. Vnthis case, however, theYz-laandeel clutch coil engages the clutch member 93 with the teeth 93a of a gear 93h fixed on a shaft 95 connected through beveled gearing 96 to the ram lead screw 35 to rotate the same to raise the ram in the Y-ldirection. Similarly, energization of the Y clutch coil engages clutch member 92. with the teeth 92a of a gear 92h fixed on the shaft 95 for operating the ram screw 35 in a direction to lower the ram in a Y- direction. The gears 92h, 93h are in driving relation with the shaft '76.

Another feature of the feed transmission is the provision of a rapid traverse motor and clutches to connect this traverse motor to the saddle and ram. In the present case, also shown in FIG. 2, the traverse motor is connected through a clutch 101 to the shaft 76. Energization of a T clutch coil shifts a clutch member Itlla splined to the shaft 76 into engagement with a gear Iilb operated by the traverse motor through a gear Ifile. This will drive the shaft 76 at a fast speed for rapid traverse of the saddle or ram. One of the feed clutches 82 in the feed transmission is constructed so that with neither of the actuating FCI-F or FCI-S clutch coils energized, the clutch 82 is in neutral thereby disengaging the feed transmission. Suitable interlocks and controls are provided, as will be described hereinafter, to insure that this feed clutch 32 is disengaged and in neutral when the traverse motor is connected in drive relation to operate the shaft 7d.

Illustratively, feed rates of between .0067 inch per revolution of the table to .144 inch per revolution of the table may be provided with the feed transmission shown, with particular combination of the five feed clutch coils FCI-F, FCI-S and FC2-FC4 actuated. It will be noted that the feed rates are expressed in Inches Per Table Revolution in view of the fact that the speed of the input gear 'i2 depends on the speed of the table 2i. The absolute feed rate or velocity in Inches Per Minute at which the saddle 3i) or ram 31 moves depends upon both the setting of the speed transmission and the setting of the feed transmission.

MACHINE TOOL CONTROL Referring to FIGURE l, a control console MIZ is illustrated on the right-hand side of the machine tool shown in this gure. machine tool is further provided which has the controls for operating the table transmission in the form of RUN, STOP and J OG buttons.

The control console IGZ provides mean operative through the control system to select the saddle or ram for operation and direction of movement and to select the feeds and speeds of the saddle, ram and table. Such means includes a pushbutton keyboard or control panel 106 on the front of the console for actuating control system switches, herein shown in microswitches mounted on a movable panel carriage M37 supported behind the face of the panel. A fragment of the console pushbutton keyboard is illustrated in FIG. 3, and the panel face is broken away in FIG. 4 to show the carriage 107. Referring to these figures, at the left side of the panel Idd there are found vertical rows of UP-DOWN-IN and OUT pushbuttons U, D, I and O for actuating control system switches IS, OS operative to energize the Z-}- or Z- clutch coils for coupling the feed transmission to the saddle lead screw 36 thereby to operate the saddle, and for actuating control system switches US, DS to energize the Y-I- or Y- clutch coils for coupling the feed transmission to the ram lead screw 35 thereby to operate the ram. Such switches are found in the control system schematic wiring diagram of FIGS. 21-23 to which references may also be made. Compound motion of the cutting tool at 45 relative to the Z and Y axes is provided by moving both the saddle and ram; the invention will be applied in simplified form to a two-dimensional system, although it will be readily understood the invention may be further applied in a straightforward manner to A table speed control panel idS at the 6 further operation of the cutting tool in the X direction where required in connection with a particular machine tool.

Controls for power indexing the turret are included in the form of a vertical row of rotatable switch actuators IND for indexing the turret to any one of ve turret positions for each machining step.

At the right-hand side of the panel Ide is found vertical rows of pushbuttons under the legends FEED and SPEED for selecting feed rates for the saddle and ram, and for selecting table speeds. By operating combinations of the Feed select pushbuttons FI-4 in one line with the carriage 107 behind that line the feed select switches FSI-4 carried by the carriage are actuated to energize combinations of the feed clutch coils FC-S, FCI-F and FC2-FC4 and thereby obtain any one of sixteen feed rates for the saddle and ram. Similarly, by operating combinations of the Speed select pushbuttons SI-i in the same line, the speed select switches SSI-4 are actuated to energize speed clutch coils SCM and SCI-S04 and thereby obtain a desired table speed.

Saddle and ram operation Turning first to the pushbutton actuated controls for the saddle and ram, as hereinbefore mentioned, the left side of the panel carries UP-DOWN-IN and OUT pushbuttons U, D, I and O for operating the Z-tand Z- clutches for the saddle or the Y+ and Y- clutches for the ram. These pushbuttoms are arranged in vertical rows; the first row R at the left is for resetting; the second and third rows are associated with the ram 31 to permit selection of either up or down movement of the ram. The fourth and fifth rows are associated with the saddle Si? to permit selection of either in or out movement of the saddle.

The sixth vertical row of buttons is for indexing the turret to any one of ve positions. The seventh row, T, permits selection of the fast traverse speed for the ram or saddle. Only the pushbuttons in a single horizontal line are effective together to control a single machining step.

It will readily be understood, therefore, that a cutting tool in the turret of the machine tool may be moved up -or down in a manually controlled machining step, by punching the UI) or DOWN button U, D, in one of the pushbutton lines at the control panel. In a similar manner, in or out movement or movement at 45 may be obtained by punching the IN or OUT button, I, O or combinations of the UP-DOWN-IN or OUT buttons, respectively. To stop the saddle or ram, the left hand reset button R for that line is punched in to release the UP-DOWN-IN or OUT button. End point selection, it will be observed, in a manually directed machining step is achieved under the direct guidance of the machinist by his stopping `the cutting tool and measuring the workpiece or otherwise checking the piece to determine whether the machining step has been completed properly. Setting in data for carrying out this step `in the repeat cycle requires that a certain combination of UP-DOWN-IN and OUT buttons be restored, whichever produce the desired direction of movement.

Turret indexing Adjacent and to the right of the rows of UP-DOWN-IN and OUT pushbuttons is found the vertical row of rotary actuators IND for selecting turret positions. Details of a suitable power turret may be found in Conover Patent No. 2,936,656. Means for operating the turret motor is incorporated in the control system (FIGS. 21-23), and comprises a simplification or straightforward modification of the control means described in detail in said Conover patent to position the turret by power responsive to the angular setting of the rotary actuators IND. Such simplified means is herein shown as selector switches with contacts INSI-S which are carried by the panel carriage 107 at a point behind the'vertical -row of actuators IND so that means such as a wiper arm MS mounted on each actuator IND and angularly positionable at one of ve positions corresponding to turret index positions, bridges between contacts zero and one of the numbered switch contacts INSl-- These selector switch contacts are energized only with the ram at its uppermost position to avoid the danger of a rotating tool striking the work; a second set of normally open limit switch contacts Y-l-lim-Z are provided to make it impossible to index the turret unless the ram is at its uppermost position whereby such contacts are closed.

While in the control means illustrated in said Conover patent means is also provided to select direction in which the turret will be indexed, it will be readily understood that this latter means may be set permanently in either position as desired so that the turret will always be rotated in one direction to the selected position for a particular machining step.

The limit switches LS1-5 (FIG. 2l) in seriesrwith each of the selector switch contacts INSl-S are associated, respectively, with the live turrent positions so that one of such switches is actuated to open the contacts thereof for each turret position. Illustratively, the turret is at position one thereby opening the first limit switch LSE. To index the turret from this position to any other of the five positions, the operator manually sets the rotary actuator lND in one line of the pushbutton keyboard to an angular position corresponding to the desired turret position. This bridges the selector switch contacts Zero to the same numbered contact as the desired turret position. When the limit switch for the ram is actuated to close its second set of contacts Yllim-2 energizing the turret selector switch INS, a circuit will be completed through the same numbered contact as the desired turret position and the same numbered normally closed limit switch LSE-5 thereby energizing the turret indexing solenoid M39 and starting-the turret motor. This rotates the turret body. Such rotation will continue uninterruptedly with-out pause until the limit switch which is in circuit with the energized selector switch contact INSl-S, is operated.- Upon operation of this limit switch, the contacts of the limit switch will open to deenergize the turret'motor solenoid lil?. When this solenoid is deenergized, its contacts 169-1 will drop out thereby stopping the turret motor.

Modil'ications or simplifications of this turret control to accommodate the present control system, are contemplated. For example, the usual step-by-step turret indexing means may be incorporated and arranged to be responsive to an indexing pushbutton instead of a rotary actuator IN. With such an arrangement, an indexing solenoid will be energized when the indexing pushbutton of a line on the panel is latched in thereby causing the turret to advance one step. Other modications or simpliiications will be readily apparent, as, use of a conventional sequencing mechanism cam powered by the last bit of Y-axis motion.

Feed and speed selection feed rates for the saddle or ram.

By means of pushbuttons at the left of the panel, the ram and thereby a cutting tool in the turret may be moved up or down by punching the UP or DOWN button U 011D in one line behind which the carriage MW is posid tioned, or may be moved in or outby punching the IN or OUT button I, O in the same line. The cutting tool may also be moved at 45 in the two-dimensional control system here illustrated by punching one of each ot' the UP-DOWN or lN-OUT buttons. The table speed during such operation, and the feed rate at which the saddle or ram will travel is set by the Feed select pushbuttons and Speed select pushbuttcns on the same line. Each horizontal line Vof pushbuttons, therefore, provides means for controlling the machine tool elements so that a cutting tool may be operated at any feed rate with any table speed available using the transmission with which the machine tool is equipped.

End point position selection The block of pushbuttons in the center of the panel we, hereinafter referred to as the End Point Position block, starting at the left with R and N and ending with .G01 provides means operative through the control system for end point selection. Such means is used for carrying out a machining step automatically in the repeat or mimic cycle. One of the major features of this -invention is that Vsuch means may be utilized to record the end point reached by the cutting tool during a machining step carried out under the manual direction of the machinist so as to serve as the address for the cutting tool in that same machining step repeated automatically.

Toachieve this result, each horizontal line of buttons in the End Point Position block serves as means operative through the control Vsystem to provide a signal in binary digital form representing the end point address for the cutting tool in an individual machining step. Such end point is measured along the Z or Y axis with relation to a reference position R wherein the saddle is at the righthand side of the machine tool, as viewed in FIGURE l, and the ram is raised. The End Point Position block to this end includes four groups of buttons for recording or lselecting cutting tool end point positions with graduated degrees of accuracy.

Each End Point l-osition pushbutton actuates 'bistable means in the control circuit, herein shown in FIGURES 22 and 23 as a four pole double throw switch carried by the carriage N7. The state of one set of each switch contacts represents one binary digital code place of an end point address aiong the Z axis while the other set of contacts represents the same binary digital code place of an end point address along the Y axis.V

By means of the control system described in a later ection in more detail, in the automatic repeat cycle, with combinations or" the pushbnttons in one line of the End Point Position block punched in or latched in by the keyboard mechanism, the cutting tool may be stopped to complete a machining step at any end point with 64 inches measured along the Y or Z axis from the reference point R within an accuracy of about .001 inch, although this is exemplary only and maybe modified, by adding or subtracting pushbuttons and associated control system components, Vto suit the particular machine tool with which the control happens to be associated. Furthermore, the panel shown in FEGURE l provides means for control of as many individual machining steps as there are lines of pushbuttons ywith all or" the information as to a single machining step contained in a single horizontal line.

Pushbuttolt keyboard mechanism A ln carrying out the mimic feature of the invention, each machining step of a program making up a machining vprocess may be carried out under manual `direction and the information as to each such step required to carry rout the same step later in a repetitive manner may be punched into the pushbutton keyboard of the control console Zitti?. which serves as a memory device yto record ,the machining data and also as a means, in conjunction vwith the control system, for directing the machine tool in the repeat cycle to automatically machine a new workpiece. For this purpose the control console lll?. includes mechanism by means of which the information as to a single machining step will be retained in the form of latched-in selected pushbuttons 4of a line on the panel, to be utilized to direct the operation of the machine tool to repeat the machining step.

Now referring to FlG. 4, the face of the panel lil-6 is broken away to show what lies behind the pushbuttons. Behind the top of the panel between side frame members 120, 12.2 there is mounted a shaft 124 having `a handle '126 at one end for manual operation and carrying a pair of sprockets 12?, 13@ driving, by means of chains 132, 134, sprockets i3d, 138 on a similar shaft 14@ behind the bottom of the panel. Connected between the chains by fastening means to an individual link of each chain so as to be movable up and down by turning the shafts and chains, is the panel horizontal carriage it?? which supports a series of switches, herein shown as snap-acting microswitches, aligned res ectively with the vertical rows of pushbuttons. The arrangement is such that a microswitch will be closed when an aligned pushbutton is punched in or when a pushbutton is in the latched-in position when the carriage is brought behind that pushbutton line. Thus the left-hand switch US is located behind the U vertical row of pushbuttons (FIG. 3), the second switch DS is behind the D vertical row of pushbuttons, and so on. Referring also to FlG. 5, the group lof four switches at the left side of the carriage lil? are behind the rows of pushbuttons U. D, l and O (there is no switch behind the reset buttons) so as to be selectively actuated when selected pushbuttons of this group are punched in.

As shown in FIG. 5, means are further provided to latch the buttons of the panel lilo when punched in, herein shown as horizontally slidable latch plates ldd behind each set of buttons. Each plate 146 is spring-biased toward the right such that when any button is punched in, the tapered neck thereof cams one latch plate ldd to the left to allow the button to move to its in position with the peripheral slot l@ in the of the plate i146. The plate i456 by the spring ldZ into the slot in the button to hold the button in. A reset button R is provided with each set of buttons to release or cancel one or more depressed buttons of a set and has a similar tapered neck ldd to shift the latch plate lili-t3 toward the-left thereby releasing such pushbuttons. lt will be readily seen that considering a 'horizontal line of buttons, with the carriage 167 behind that line, selected ones of such buttons may be punched in manually thereby closing the contacts of the corresponding microswitches on the carriage M7 and establishing all the requisite information for the machine tool to carry out a machining step, and such buttons will be latched in to hold the information.

The panel carriage lil? is movable vertically, in the present case, so as to be positionable at the level of each horizontal line of pushbuttons. The carriage may be moved manually by means of the handle 126, to position the carriage as desired. Means are also provided to move the carriage automatically. With automatic carriage movement, succeeding machining operations, the information for which has been earlier punched in, may be repeated as the carriage moves down behind the panel face from line to line of the pushbuttons. in the repeat cycle, as the carriage moves from behind the pushbuttons at one level to the pushbuttons at the next lower level, the switches on the carriage are deactuated and then reactuated according to the buttons punched in in the new rank.

To shift the carriage 107 to carry out succeeding machining steps completely automatically, the control system includes an N (next) solenoid which, in one stroke of the solenoid through a ratchet mechanism 156 (HG. 4), turns the lower shaft 140 sufliciently to step the carriage from one liner to the next lower line of panel pushbutis automatically pushed button in the plane Y tons. Each line of pushbuttons in the control panel End Point Position block also includes a button N which, through a microswitch on the carriage N7 operates the N solenoid. The button N of any line when latched in designates that the next machining step will be carried `out immediately following the completion of the step for which the data is stored in that line.` To this end, the pushbutton N is effective to deenergize the N solenoid at the completion of a machining step, thereby to step the panel carriage to the next lower line of puslibuttons reserved for the succeeding machining step fully automatically. In the usual repeat cycle for a plurality of machining steps, such as the twenty steps shown diagrammatically in FlGS. 24-28, after each machining step is completed the carriage is automatically stepped by the N solenoid and ratchet mechanism 356 from one to another linc of pushbuttons. After the machining step established by the depressed pushbuttons of the first line is completed, for example, the carriage is shifted to the second line; after the machining step for which the data is stored in that line is completed, the carriage is shifted to the third line; and so on.

End poi/it position Signal Lamps Another feature of the invention, the importance of which will appear as this description proceeds, relates to provision on the control panel for visually indicating the instantaneous position of the cutting tool. Referring to HG. 3, this is achieved, in general, by operating a set of signal lamps ll'tl, one over each vertical pushbutton row in the End Point Position panel block, from means associated with the saddle lead screw 36 and ram lead screw 35. Thus, illustratively, as the saddle lead screw 3d rotates to advance the saddle 3? toward a workpiece on the table, or the ram lead screw rotates to advance the ram 3l, the signal lamps over the End Point Position blocl; flash on and olf to give visual indication of the instantaneous position of the cutting tool. It will be readily understood that the condition of the lamps at any given instant provides positional information in binary forni according to whether each signal lamp is on or off. The signal lamps are similarly actuated when both the ram and saddle are advanced to move the cutting tool at 45 to the Z axis; however, the master axis in the present case is the Z axis so that the Z coordinate of the instantaneous position of the cutting tool (designating the saddle position) is represented in binary by the condition of the signal lamps at any particular instant when both the saddle and ram are operating to position the cutting tool.

ANALGG TO DIGITAL CONVERTERS For cooperation with the End Point Position selection means, which provides a signal in binary digital form, or code, representing selected end point, according to the present invention an improved means is included for representing in like binary digital form, or code, the instantaneous position of the saddle and ram for comparison with the end point signal, to the end that the cutting tool will be guided by such comparison automatically to the selected end point. Such improved means for indieating the instantaneous position of each of the Saddle and ram, herein shown as an analog to digital converter mounted for operation by each lead screw, is also used to actuate the End Point Position signal lamps 170.

Referring to FG. l, the converter on the ram lead screw 35 is referred to hereinafter as the Y converter, while the converter on the saddle lead screw 36 is referred to hereinafter as the Z converter. Such converters, in the present case, provide sets of electrical impulses representative, in consecutively higher binary digital code places, of the instantaneous angular disposition of the associated lead screw, thereby providing positional information as to the cutting tool. Since the Y and Z converters are similarly constructed, the following description will be conned for the most part to -machine tool shown in FlGURF 1, accordingly, each converter (FIG. 6) includes four sections corresponding, respectively, with the four groups of pushbuttons in the End Point Position block of the panel, and identiiied as the Fine, Medium Fine, Medium Coarse and Coarse sections. Each section includes a stack of cams 175 driven from one leadscrew at a preselected speed ratio through a transmission section 177.V Such stacks of cams are associated, respectively, with sets of converter switches 179. The stacks of converter cams `175, through the sets of converter switches 179, produce lead screws positional data of graduated accuracy.V

' biased toward the rollers.

In carrying out this invention, to provide positional Y data in usable form and representing saddle travel within the requisite degree of accuracy, with a saddle lead screw having a 1/2 inch pitch the cam stack 175MF for the Medium Fine switches is driven directly by the saddle lead screw. The cam stack for the Fine switches is driven faster than the lead screw through an up drive having a 16:1 ratio, while the cam stacks 17SMC and 175C for the Medium Coarse and Coarse switches are driven slower than the lead screw through step-down'drives providing 16:1 reduction and 256:1 reduction, respectively. With such converter transmission drive ratios and converter cams constructed as described in detail later, the states ofthe switches Y179 starting with the Fine set 179F and ending with the Coarse set 179C, represent consecutively higher places of the binary digital code. Each switch 179 is `actuated by one cam 17S so as to represent the digit of yone binary place in said code. With this arrangement wherein converter switches are directly actuated, itrhas been found that commercial microswitches, such as GE Switchette, series 103, Vare suitable; the Vswitches selected for such purposes should, of course, be rated for the rela,- tively heavy currents of clutch and brake lcircuits in which as will be described in more detail later, the converter switches 179 kare connected.Y

Converter cams As shown diagrammatically in FIGS. 15-18, each converter section includes a stack of four cams, herein shown as annular arrays of rollersrlitl. Each annular set of rollers contacts cam Vfollowers in the form Vof spring 186A-E carrying rollers 18d' in circular array around the periphery. Taking the Fine switches cam stack as illustrative, fourswitches 17d-1A are provided staggered the drawings.

at about the cam stack to accommodate space limita- 180, the lirst switch179-1, which is the top switch in 1-2 Y this result, such first switch 179-1 is actuatedrby the irst annular set of rollers at the left-hand end of the cam stack as viewed in FIGS. 6, 7 and 14, which set includes sixteen rollers 131i equally spaced around the periphery, as shown in'FlG. 15. Still referring to FiG. 14, such `rollers may be ordinary roller or ball bearings mounted on pins 1&3 supported by the cam discs so as to provide friction-free Contact with the finger followers 182 spring Square spacers V19d are provided to hold the cam discs 1ti6A-E separated suliiciently to allow the rollers to turn freely and the cam discs are held in assembly by pins 192 passing through the corners of the spacers.

To obtain the requisite oscillating action of the nger followers 152 wherein the linger 182-1 of the first cam is operated to actuate the microswitch as each roller passes, a crimp is provided in the linger providing an offset portion 1% narrow enough to enter between adjacent rollers as the cam rotates, and extending far enough so that as the crimped portion rides over the high Ypoint of a roller, the baclr Vof the i'inger actuates the first microswitch. ln FIG. 13 the complete details of each follower are shown. Each follower includes a wide section rotatably supported onV a rod 194 and extending the full length of the cam stack. A narrow section providing the iinger contacting the rollers extends therefrom ata point located axially in alignment with the particular cam with which the follower is associated. As noted before, the length of the linger depends on the converter switches with which the iingerhappens to be associated. The long linger 152-3 is shown in solid lines in FIG. 13 for the third converter switch 179-3 of either the Fine or Medium Fine converter switches, while the location for the other fingers is shown in phantom. The button 18d-3 on the third microswitch is shown in dotted outline. With such a follower construction, in FlG. 12, which is a sectional view taken through the Medium FineV section, the wide portion of all four followers 1522-1 to 4, appears in the view with only the narrow finger extending therefrom for the fourth converter switch also appearing in the view.

By providing sixteen cam rollers 13d in the iirst set, the rst Fine switch 179-1 is actuated sixteen times each revolution of the carri stack. With a saddle lead screw having a pitch of .1/2 inch per revolution, the saddle lead screw makes two revolutions per inch of saddle movement. The first Fine switch 179-1 is thus actuated five hundred and twelveY ons per inch of saddle travel (16 x 32 '-512)l and ve'hundred and twelve olfs providing one thousand and twenty-four changes of state of this Fine switch per inch of saddle travel. Each change of kstate of such first Fine switch 179-1 thus represents V102., inch, or'about .001 inch of saddle movement, and the position of thesaddle within aboutV .001 inch from the reference. A Y

The chart of FlG. 19 diagrammatically depicts the successive Vchanges of state of the first Fine switch 179-1 in the left-hand column. actuated state of this converter switch, while zero represents Vthe deactuated state of this'switch. Reading down in the left-hand column, it will be seen that the switch changes state for eaclrl/logak inch of saddle movement.

Moreover, the instantaneous Ystate of this switch for any saddle position may readily be determined from this chart, although only the most significant dimensional increments are included so that a picture of the states of all sixteen switches can be given within the spacial limits of Thus the state of' this first Fine switch at .ll/(p, inch and /g inch is shown, aswell as the vstate .001 inch short of such increments.

ln the arrangement herein illustrated for the Z conyerter, eachjactuation'of the second Fine switch 179-2 FIG. 11, represents by a single change of'state between Y off and on position, the smallest increment of saddle inovement registered in the illustrative converter: that is, ap-

represents approximately .002 inch Vof saddle movement. i

'lo achieve this result, this second switch 179-2, which is located 99 frornpthe first switch 179-1, is actuated by a YsecondV cam Vcarrying eight equallyV spaced rollers 180 The numeral l represents the (FIG. 16). Such cam rollers actuate the second switch 179-2 via a finger 182-2. This second Fine switch finger is provided with a long crimp providing a long offset portion 195 causing the finger to dwell in the deflected position the same length of time as in undeflected position thereby to actuate the second Fine switch 179-2 eight times each revolution of the cam stack, holding the switch actuated for the same interval it is deactuated. The second Fine switch 179-2 is thus actuated two hundred and fifty-six ons per inch of saddle travel (8X32z256) and two hundred and fifty-six offs providingy five hundred and twelve changes of state of the second Fine switch per inch of saddle travel. Each change of state of the second Fine switch thus represents 1/{312 inch, or about .002 inch of saddle movement.

Again referring to the chart of FIG. 19, it will be seen that the second column depicts the changing state f the second Fine switch 179-2 as the saddle travels. The state of this switch at various increments of saddle movement is also shown.

Also referring to FIG. 17, the third cam actuates the third Fine switch 179-3 to provide two hundred and fifty six changes of state of the latter per inch of saddle travel or about .004 inch of saddle movement for each change of state of this third Fine switch. To achieve this result. the third cam is provided by four pairs of rollers 130 equally spaced about the cam stack periphery and the follower finger 1532-3 is shaped like the finger used with the second Fine switch 179-2 with a long crimp providing a long offset 195 causing equal periods of dwell in the on and off positions. Reference may be made to the chart of FG. 19 in the third vertical column of which the changing states of this third Fine switch 179-3 is depicted.

Following the principles guiding the arrangement of cam rollers as previously described, the fourth Fine switch 179-4 is actuated by a cam (FIG. 18) provided by two sets of four rollers 186 each to provide one hundred and twenty-eight changes of state of this switch per inch of saddle travel, with each change of state of the same duration. Further reference may be made to the chart of FG. 19 wherein the fourth column illustrates the changing states of the fourth Fine switch 179-4. Such sets of rollers appear in the foreground of the view of the cam stack in FIG. 14.

The other stacks of cams are constructed in a like manner to the `cam stack of the Fine switches. Thus the stack 175MF driven directly by the lead screw and actuating the Medium Fine switches 179MF includes a rst cam provided by sixteen rollers, a secon-d cam provided by eight equally spaced rollers, a third cam provided by four pairs of rollers, and a fourth cam provided by two sets of four rollers each. The nger `followers 182 are similarly constructed with only the finger 182,-1 -associated with the sixteen roller cam having a short crimp 193. With a cam stack so constructed and arranged, and driven at the speed of the lead screw providing two revolutions per inch of saddle travel, the first of the Medium Fine switches has sixty-four changes of state (2 3Z=64) per inch of saddle travel such that each change of state represents 1/{54 inch. The second of the Medium Fine switches changes state a-t half the rate of the first such that each change of state thereof represents 1/32 inch of saddle travel, each change of state of the third of the Medium Fine Switches represents 1,/16 inch of saddle movement, and of the fourth of the Medium Fine switches represents 1/s inch of saddle travel.

Similar considerations prevail for the medium Coarse and Coarse switches. Because of the stepdown drives, the cams associated therewith rotate slower that the lead screw such that each change of state of the first of the Medium Coarse switches, for example, represents 1A inch of saddle travel (/s rev./in. i32=4 changes of state per inch of travel). Each of the succeeding three cams in the Medium Coarse set operates the associated switch 179 'idat half the rate the preceding switch is operated: that is, t0 represent 1/2 inch, l inch and 2 inches of saddle movement, respectively. In the case of the Coarse switches 179C, .the latter are operated to represent 4 inch, 8 inch, 16 inch and 3`2 inch increments of saddle travel.

Again referring to FfG. 19, as before mentioned the four left-hand columns graphically represent the changing state of the Fine converter switches for travel of the saddle. It should be apparent that the second four columns represent the changing state of the Medium Fine converter switches, the next four columns represent the changing sta-te of the Medium Coarse converter switches and the right-hand four columns represent the changing States of the Coarse converter switches. Taking the first column of the right-hand set, for example, the switch 4for which the states are shown in this column changes state for each 4 inches of saddle travel so that it remains in the deactuated state through 3.999 inches of saddle travel in either direction whereupon as the saddle completes 4 inches of movement such switch is actuated represented by the numeral l. Note that all other switches will be deactuated 'with the saddle 4 inches from the extreme travel position. It should be clear that the instantaneous postion of the saddle 31 is represented hy a unique comhination of actuated converter switches. Moreover, it is emphasized that in this case, the converter cams are rotated in the reverse direction with saddle movement from right to left so that the Z converter switches change state in a suiostractive sense responsive to such saddle movement. The foregoing also applies to the Y converter with downward ram movement.

A further feature of this converter relates to the provision of a simplified limit means defining the range of the converter. Since 180 of rotation of the Coarse cam stack 175C represents the limit of the range of this converter, this Coarse cam stack carries a fifth limit cam provided .by a single roller 199 supported by the fifth cam disc `lll. A pair of spring 'fingers 2%, 2%1 on opposite sides of this limit cam, constructed and mounted similar to the other spring fingers 182 (FIG. 13) are contacted by the roller 199 as the cam disc reaches the limit positions and are deflected to actuate Z-fand Z- limit switches carried on opposite sides oft-he cam. Simi- `lar limit means in the form of cam actuated Y-{ and Y- limit switches are provided in the Y converter.

Converter transmission Referring to FIGS. 6-12 for details of the converter transmission, the cam stacks are driven from an input shaft Zilli coupled by any suitable means to the saddle lead screw 3o providing an extension thereof. The transmission includes, as will have already been noted, four main sections: an up drive section forthe Fine switches cam stack; a direct drive section yfor the Medium Fine switches can stack; and two step-down drive sections for the Medium Coarse and Coarse switches cam stacks. T he up drive and step-down drives are planetary drives, as shown diagrammatically in FG. 6. The transmission also includes a fifth seciton at the right end of the unit as viewed in FiG. 6, relating to the auxiliary slowdown means.

(l) Fine secion Considering, for example, the Fine transmission section 1'77F appearing at the left end as viewed in FiG. 6, this section includes two planetary gear sets providing an up drive at 16:1 ratio for the Fine switches `cam stack 17:7F. Such cam stack, as hereinbefore described, includes live axially space-d annular discs lioA-E supporting rollers Btl which serve as cams. lReferring also to FlG. 7, these :annular discs are assembled with spacer plates 190 and pins `192 to form a rotor which is journaled hy means of hearings 265 on the shaft and pinned to a spline 2% free 'to turn on the shaft 294 and serving as the sun gear for the secondary planetary gear set. The 

1. IN A SYSTEM INCLUDING A MACHINE TOOL AND MEANS FOR CONTROLLING THE TOOL TO PERFORM A SERIES OF MACHINING STEPS IN ACCORDANCE WITH A STORED PROGRAM, THE COMBINATION COMPRISING: A MOVABLE TOOL ELEMENT, A SOURCE OF POWER FOR POSITIONING SAID TOOL ELEMENT ALONGA PARTICULAR AXIS, AN ANALOG TO DIGITAL CONVERTER OPERABLY CONNECTED TO SAID TOOL ELEMENT FOR PRODUCING A SET OF IMPULSES REPRESENTING IN BINARY DIGITAL CODE THE INSTANTANEOUS POSITION OF SAID TOOL ELEMENT ALONG SAID AXIS, PROGRAM RECORDING MEANS ADAPTED TO RECEIVE MANUALLY SET-IN DATA FOR EACH MACHINING STEP AND INCLUDING A PLURALITY OF LINES OF BISTABLE ELEMENTS WITH THE ELEMENTS IN EACH LINE BEING MANUALLY OPRABLE TO REPRESENT IN LIKE BINARY DIGITAL CODE A DESIRED END POINT POSITION FOR SAID TOOL ELEMENT INA SINGLE MACHINING STEP, AND CONTROL MEANS INCLUDING MEANS FOR COUPLING SAID POWER SOURCE TO MOVE SAID TOOL ELEMENT TOWARD THE DESIRED END POINT IN EACH MACHINING STEP, A COMPARISON CIRCUIT FOR CONNECTION BETWEEN EACH LINE OF BISTABLE ELEMENTS AND SAID CONVERTER AND EFFECTIVE TO PRODUCE AN OUTPUT PULSE RESPONSIVE TO IMPULSES FROM SAID CONVERTER MATCHING THE STATES OF SAID BISTABLE ELEMENTS IN ONE LINE, MEANS FOR UNCOUPLING SAID POWER MEANS TO STOP SAID TOOL ELEMENT AT THE COMPLETION OF EACHMACHINING STEP RESPONSIVE TO SAID OUTPUT PULSE, AND MEANS FOR CONNECTING SAID COMPARISON CIRCUIT SUCCESSIVELY TO EACH LINE OF BISTABLE ELEMENTS FOLLOWING THE COMPLETION OF EACH MACHINING STEP. 